IN 2005, Kenneth Lander, moved with his wife, stepdaughter and the youngest three of his seven children to a coffee farm in Costa Rica[6]. “It was like Swiss Family Robinson,” Mr. Lander jokes. “We just left.”

The ripples from a crash in farmland prices would not have the long-lasting effects on the economy that the subprime debacle did, but the chance of a crash in farmland prices should still concern policymakers.